Electric switch



April 16, 1935. F. A. WEIGEL 1,998,403

ELECTRIC SWIYTCH Filed Aug. 16, 1933 2 Sheets-Sheet 1 lnve ntor" His Atorney.

April 16, 1935. F. A. WEIGEL ELECTRIC SWITCH Filed Aug. 16, 1933 2Sheets-Sheet 2 me /20 #5 0a //4 3 y -l 6 r n W P o 2Q i mw d H my Fb 9w4% C 5 zwminw Fig.6.

Patented Apr. 16, 1935 UNITED STATES PATENT oi-rlcE ELECTRIC SWITCHFrederick A. Weigel, East Lynn, Mum, alsignor to General ElectricCompany, a corporation of New York Application August 16, 193:, SerialNo. 885,360

14 Claims. (Cl. 115-294) The present invention relates to electric itsnormal position until the film cut-out is switches and especially toautomatically operrenewed. ated electric switches for disconnecting froma A further object of my invention is to provide series circuit aportion of the circuit in case an improved switch structure wherein therethe current therein fails and closing a shunt newal oi the iilmcut-out and its insertion into I circuit around such portions so as tomaintain position serves automaticallytorestore the switch the remainderoi the circuit continuous. structure to its normal position.

One application of my invention is in connec- A further object of myinvention is to provide tion with what are termed usually cut-out animproved switch structure wherein upon inswitches for series lightingcircuits and accordsertion oi the renewed film cut-out the shunt l0ingly, I have speciflcallyillustrated and described circuit ismaintained closed until the connection my invention applied to this use.It is to be unbetween the main circuit and the loop is fully derstood,however, this is only by way of example established. and that theinvention is not limited thereto A further object of my invention is toprovide necessarily. an improved switch, the operation of which is 15 Inconnection with series lighting circuits, for controlled by a filmcut-out, the arrangement example, series street lighting circuits, 0.large being such that the switch will operate in renumber of lamps maybe placed in series along a sp use to a break in the loop circuit, butwill not main street and at intervals there may be what Operate merelyin p e to the failure of e are termed usually loop circuits extendingdown p in at Ci cuit. 20 side streets, these being in substance a partof Other objec s d the advantages 0! my inand in series with the circuitextending along vention will be apparent and the invention itself themain'street but being in the form of a loop will be better understoodfrom the following dein that the series circuit extends down the sideseriptien. when e ed in connection with street and back again to themain street. It at e ac p y w s. and the features of 25 any time, thereoccurs a fault, such as an open novelty Which characterize my ventionwill be circuit, in a loop circuit, it is desirable to disconpointed Outwith particularity in e claims anriect the loop circuit from the circuiton the main ne d t and forming a p f t s specification. street and closea shunt circuit around the open Referring to the drawings, ig- 1illustrates a end of the loop so as to maintain the continuity sideelevation of a series cut-out switch provided 30 of the remainder of theseries circuit, 1. e., the with a latching mechanism built in accordancecontinuity of the series circuit on the main street. with y invention; 2is a ront Sectional view Also it is desirable that the switch maintainsuch along line of g- 3 is a horizontal connections until the fault inthe loop circuit has Section taken along line of g- 4 is been correctedafter which the shunt circuit may a diagrammatic illustration of thecircuits, switch 35 be again opened and the loop circuit connectedmechanism and the latching mechanism showing into the main seriescircuit. the switch in closed position; Fig. 5 is a diagram- One objectof my invention is to provide an matic illustration similar to Fig. 4,showing the improved switch structure whereby in case the switch latchedinto n Position, and t;- 6 is a current in the loopcircuit fails, due toan open sectiqnel Y line 2 looking in 40 circuit, for example, the loopcircuit is automatithe filrectlon the arrowscally disconnected and ashunt circuit is closed Flgs' 2 and 3 or the drawmgs illustrate m aroundthe loopcircuit to maintain the continuity tail i g- 3? 5 g f g Seriesof the main circuit and wherein after operating, cut'ou SW1 avmg mova 8to members 5 the Switch is mechanically Rhea in its new Ill and II forconnectinga loop circuit including 4 position so that. even though thecurrent is conductors l2 and H to a main circuit including conductors lland IS. A switch member I6 is stored in the loop circuit, the switchwill not be provided to shunt the conductors n and n and returned t ItsPj posit'lon but must be connect the conductors it and is to each otherreset to Such Posmon manually under certain conditions. A clearunderstanding 50 Another object of my nv n on is to pro of the circuitsmay be had by inspection of Figs. an improved switch structure, theoperation of 4 and 5, I

which is controlled through the intermediary of Th it h ber In i ted ona shaft n,

a film cut-out, the arrangement being such that slidable in bearingslocatedinthe insulating blocks the switch after operating cannot berestored to It and I9 and is biased toward the closed position by aspring 28. In this position the switch member connects to each other thecontacts 2| and 22 which are mounted on the insulating block I9 and areconnected to conductors l2 and I4, respectively. The switch member I8 ismoved to the open position by an armature 23 to which is attached aninsulating member 24. This member 24 engages and moves the shaft l1 whena magnet coil 25 is energized. When the magnet coil 25 is deenergizedthe armature 23 is moved away from the shaft H by a spring 26, thearmature being pivoted on a U-shaped bracket 21 which also supports thecoil 25 and the insulating block I8. The insulating block I is attachedto the bracket 21 by a screw 28 and supports block l8 which is attachedto it by screws 28.

The switch member is operated by apparatus similar to that whichoperates the switch member l8. It is mounted on a shaft 38, slidable inbearings located in the insulating blocks 3| and 32 and is biased towardthe closed position by a spring 33. In this position the switch member Iconnects to each other contacts 34 and 35 which are mounted on theinsulating block 32 and to which are attached conductors l3 and l5,respectively. The switch member is moved to the open position by anarmature 36 to which is attached an insulating member 31 arranged toengage the shaft 38. This member 31 engages and moves the shaft 38 whenthe magnet coil 38 is energized. When the magnet coil 38 is deenergizedthe armature 36 is moved away from the shaft 38 by a spring 39, thearmature being pivoted on a U-shaped bracket 4| to which the coil 38 andthe insulating block 32 are attached. The insulating block 32 isattached to the bracket 4| by a screw 42 and supports block 3| which isattached thereto by screws 43.

The frame of the cut-out switch consists of two insulating members 45and 46 which may be of wood or other suitable material, and are equippedwith brackets 41 and 48 by means of which the entire switch may besupported in any convenient casing (not shown). The members 45 and 46are attached to each other at their respective lower ends by plates 58and 5| which are attached to the members by screws 52. The members 45and 46 are respectively attached at their upper ends to lugs 53 and 54of a socket 55 which will be dedscribed presently.

As stated above, the switch member 6 is arranged to connect theconductors l4 and I5 to each other under certain conditions. The switchmember for this purpose is rigidly mounted on a shaft 51 slidable inblocks 58 and 58, and is arranged to engage contacts 68 and 6| connectedrespectively to conductors I4 and I5 by short leads 62 and 63. Thecontacts are mounted on the block 58 which is similar in shape to theblocks 19 and 32, as clearly shown in Fig. 6. The shaft 51 is biasedupwardly by a spring 66 which acts against the switch member I6 and theblock 58. The block 58 is attached to the block 59 by screws 68. Theblock 59 and thereby shaft 51 and the contacts 68 and 6| may be slightlyraised or lowered on the frame members 46. The block 59 is slidable onthe member 46 in a groove therein defined by the walls 61. It may beslighlty raised or lowered by a screw 18 mounted in a block 1| which isrigidly attached to the member 46. If it is desired to adjust the block,a screw 12 extending through a hole in the block 59 and a slot 68 in themember 46 is loosened and the screw 18 is turned until the block 58 andthe shaft 51 are raised or lowered the desired amount, after which thescrew 12 is tightened. The slot 68 in member 46 through which screw 12extends is made long enough to give the desired range of adjustment forthis purpose.

-As shown in Fig. 2, the shaft 51 is held against its bias by a shaft 15which engages the upper end of the shaft and thereby holds the switchmember l6 separated from the contacts 68 and 6|.

The shaft 15 is slidably mounted in bearing lugs 16 and 11 attached to aplate 18, which in turn is attached to the insulating member 46, byscrews 19, and supports the latching mechanism which will be describedlater in this specification. At its lower end the shaft projects throughthe lug 11 and engages the shaft 51 and at its upper end it projectsthrough lug 16 and into the socket 55.

The socket 55, as stated above, is rigidly attached to the members 45and 46 by means of its lugs 53 and 54. tacts 88 and 8|, each comprisinga series of leaves attached to the socket by a screw 82 and connectedrespectively to one side of the coils 25 and 38 by conductors 83 and 84and connection strips 85 and 86. The contacts 88 and 8| are of the typegenerally used in series sockets being biased towards each other and arearranged to be separated by and to engage prongs 81 and 88 mounted in aholder 88.

The prongs 81 and 88 are metallic strips mounted parallel to each otherin a holder 88 in which they are rigidly mounted and insulated from eachother. The prongs are arranged to support a film cut-out device 8 whichis inserted between them. This device 9| comprises a pair of metallicdiscs separated from each other by an insulating film. The insulatingfilm may be a film of metal oxide or any other suitable insulating filmwhich will insulate the discs from each other under normal conditions,but will break down and permit current to pass if a predeterminedvoltage above normal is applied. I prefer to use for this purpose acut-out device, such as is described and claimed in U. S. Patent1,784,656, Butler, issued December 9, 1930.

The prong 81 is slightly longer than the prong 88 and engages the upperend of shaft 15 when the holder 88 and the prongs are placed into thesocket, as shown. In this position the lower end of the shaft 15 forcesthe shaft 51 down and separates the switch member l6 from the contacts68 and 6|.

In automatically operated series cut out switches, it is desirable tomaintain the terminals of the circuit section, which have been separatedfrom the main circuit by the switch, separated from the main circuit,irrespective of the current in the coils which originally opened theswitch. If the switch should accidentally close during the time repairsare being made to the circuit, potential will be applied thereto andmight injure the workman. I, therefore, provide in accordance with myinvention an improved latching device which will maintain the switchopen independently of the energy in the coil which opened the circuitand will maintain the switch in the open position until the switch isagain reset by hand.

The latching device comprises a pair of bell cranks I88 and IM pivotallymounted at their respective vertexes on pins I82 and I83 located inplate 18. The one arm I84 of the bell crank I88 is provided with anextension I85 which extends between the member 24 and the shaft l1 sothat when the shaft I1 is moved to the open position by the armature 28and the member 24, the bell crank is moved counter-clockwise It isprovided with a pair of conabout its pivot. The second arm I06 of thisbell crank I is provided at its end with a lug I01 and a notch I08. Whenthe switch member I0 is in the closed position'at which it engages itscontacts, the bell crank is held positively in the position shown inFig. 2, by latching pawl I09. The latching pawl I 09 is pivoted on a pinIIO which is also mounted on the plate 18 and is biased towards the bellcrank by a spring III which is under tension and attached to the arm I06and the pawl I09. In the position shown, the pawl I09 engages the end ofthe arm I06 whereby the pawl cannot turn clockwise because of thetension of spring III. In this position the pawl I09 also engages theunderside of the lug I01 whereby the arm I06 cannot turn clockwise byaction of the spring III. When the armature 23 is attracted, the member24 moves the extension I with the shaft I1 and thereby raises the armI06 untilthe latching pawl moves into the notch I08 thereby preventingthe return of the switch member III to the closed position.

The bell crank IN is similar to bell crank I00 and is provided with anarm II2 to which is attached an extension I I3 extending between theshaft 30 and the member 31 which is attached to the armature 36. Thesecond arm II4 of the bell crank IOI is provided with a lug H5 and anotch II6. In the position shown in Fig. 2, this bell crank IOI is heldin position by a latching pawl II1 pivoted on a pin I I8 and biasedtowards the arm II4 by the spring II9 which is under tension and isattached to the arm H4 and the pawl II1. In the position shown, the pawlII1 engages the end of the arm II4 under the lug I I5. When the armature36 is attracted, however, the arm I I4 is raised similarly to the armI06 and the pawl II1 moves into the notch I I6 thereby latching the bellcrank and the switch member I I into the open position.

For the purpose of unlatching the switch members by releasing the bellcranks, a cross-arm I20 is rigidly attached to the shaft 15. To thiscrossarm are pivoted two releasing pawls I2I and I22 which are providedrespectively with lugs I24 and I25 and cam surfaces I26 and I21. arebiased outwardly by a collar I28 which engages the cam surfaces I26 andI21. This collar is loosely mounted on the shaft and is urged upwardlyby a spring I29 which surrounds the shaft 15 and is compressed betweenthe collar I28 and the bearing lug 11. When the shaft 15 is pusheddownwardly by the prong 81, the lugs I 24 and I25 engage the upper sidesof the lugs I3I 5 -and I32 which are attached to the lower ends of thepawls I09 and H1 and face the releasing pawls. When the holder 89 iswithdrawn from the socket 55, the springs 66 and I29 urge the shafts 51and 15 upwardly. The releasing pawls I2I and I22 are thereby movedinwardly so as to pass the points of the lugs I3I and I32. In order todo this the collar I28 is moved down over cam surfaces I26 and I21against the action of spring I29 to permit the lugs I24 and I25 to movetoward the shaft 15. When the lugs I24 and I25 pass the tips of the lugsI3I and I32, however, the spring I29 again moves the collar I28 upwardand the pawls outwardly. When the shaft is then pushed downward by theprong 81, the lugs I24 and I25 exert considerable pressure on the lugsI3I and I32, thereby turning the latching lugs I09 and H1 about theirrespective pivots. This movement is clockwise on pawl I09 andcounter-clockwise on the pawl H1. The pawl ends are thereby drawn out ofthe These pawls notches I08 and H6, and the bell cranks are returned totheir first described positions. Further movement of the shaft 15 causesthe lugs to slide down the upper surfaces of the lugs I3I and I32 andmove towards the shaft until they pass the tips of the lugs I3I and I32.

Figs. 4 and 5 are diagrammatic illustrations of the automatic-seriescut-out switch applied to a series circuit. The main circuit isrepresented by conductors I4 and I5 having lamps I35 in circuittherewith. The contacts 22 and 35 arethe main terminals of this circuitand the contacts 60 and H are in multiple therewith, being connectedthereto by conductors '62 and 63, respectively. A section of the maincircuit which may for convenience be called the loop circuit isrepresented by conductors I2 and I3 and lamps I36 connected inseriestherewith having contacts 2I and 34 as its terminals. In Fig. 4 theswitch members I0 and II are shown in the closed or contact engagingposition. In this arrangement of the circuit and the switch, the currentflows from conductor I4 to the contact 22, switch member I0, contact 2I,conductor I2, lamps I36, conductor I3, contact 34, switch member II,contact 35 and conductor I 5. If the loop circuit is then ruptured sothat current cannot flow in this circuit, the potential of the circuitis applied across the cut-out device 9I. This circuit may be traced fromconductor I4, conductor I31, coil 25, conductor 83, contact strip 85,screw 82, contact 80, prong 81 to one side of the device 9|; the otherside of device 9|, contact 8I, screw 82', contact strip 86, conductor84, coil 38, conductor I38 to conductor I5. The film of insulation inthe device 9I then breaks down and passes current through the circuitjust described whereby the coils'25 and 38 are energized. The armatures23 and 36 are attracted and the switch members I0 and II are moved tothe open position. At the same time the bell cranks having theirrespective arms I05 and H3 extending between the actuating armatures andthe switch members, are moved and latched into the position shown inFig. 5 by the latching pawls acting upon the respective other arms ofthe bellcranks. The switch members then cannot move back to the closedposition, irrespective of whether the coils 25 and 38 maintain theirarmatures attracted.

When the loop circuit including conductors I2, I3 and the lamps I36 isrepaired, the holder 89 is removed from the socket 55 and a new device9| is placed between the prongs 81 and 88.

When the holder 89 is removed, the shaft 15 is raised by the action ofsprings 66 and I29 and the cross-arm 6I being correspondingly raised,the pawls I2I and I22 are moved to the upper surfaces of the lugs I 3iand I32, respectively. Simultaneously the coils 25 and 38 being shuntedby the switch member I6 are deenergized and release their armatureswhich are then biased to the inactive positions by the springs 26 and39, respectively.

When the shaft 15 is again pushed down by the prong 81, the lugs I24 andI25 of the pawls I2I and I22 bear down upon the lugs I3I and I32sufficiently to rotate the pawls I09 and H1, respectively, about theirpins until they move out of the notches I08 and H6 and engage the endsof the cross-arm I20. The bell-cranks I00 and IOI are thereby permittedto rotate about their pins until the lugs I01 and H5 again respectivelyengage the pawls I09 and I I1, as shown in Figs. 2 and 4. The rotationof the pawls changes the angular relation between the lugs I24 and I25and the surfaces of the lugs I3I and I32 in such manner that a furthermovement of the shaft "I5 downwardly causes the lugs I24 and I25 toslide over the lug surfaces and to move toward the shaft I5 against theaction of the -collar I28 and the spring I29. This movement towardthe"'shaft continues until the lugs I24 and I25 pass the tips of thelugs I3I and I32. Further movement of the shaft 15 then simply permitsthe lugs to move outwardly until they assume the position shown in Figs.2 and 4.

The block 59 is vertically adjustable, as above explained, for thepurpose of establishing a proper relation between the shafts 51 and 15.When the shaft '15 is pushed downwardly by prong 81 it is arranged tofirst release the switch members I and II and permit them to connect theconductors I4 and I of the main circuit to the conductors I2 and I3 ofthe loop circuit. Upon further movement, the shaft I5 is arranged toengage the shaft 51 and open the shunt circuit about the loop circuit byseparating the switch member I6 from its contacts 60 and SI. Thisarrangement is necessary since an opening of this shunt circuit beforeclosing the connections between the loop and main circuits creates acondition similar to a broken loop circuit and naturally breaks down thefilm cut-out device before the switching operation is completed. Theblock 59 and thereby the shaft 51 is so adjusted that shaft does notengage the shaft 51 until the releasing or unlatchingoperation iscompleted and, on the other hand, is arranged so that the switch I6 isfully separated from the contacts 60 and BI when the holder 89 is seatedin the socket 55.

As explained above, the film cut -out device 9| allows current to passthrough it to the operating coils 25 and 38 upon failure of the currentin the loop circuit. The loop circuit having lamps I36 connected inseries therein will be, however, subject to current failure when asingle lamp therein fails. It would cause considerable inconvenience tohave the circuits disconnected because of a failure of a lamp and forthis reason a film cut-out I39, similar to the cut-out SI, is providedfor each lamp I36. The cut-out I39 is inserted between the prongs of aseries type of socket and is thereby in shunt to the lamp filament. Thistype of socket and the method of inserting the cut-out device I39 iswell known in the art. It is illustrated and described in detail, forexample, in the U. S. patent to Butler, 1,713,215, issued May 14, 1929.I have therefore shown this only diagrammatically in Fig. 5 of theaccompanying drawings.

If the filament fails the voltage across the terminals of the seriessocket increases and the insulating film of the cut-out device breaksdown at a predetermined value. This value is lower than that at whichthe cut-out 9I fails. In one particular instance. for example, thecut-out I39 is constructed to fail at 100 volts and the cut-out 9| at1000 volts. This allows a leeway such that if the current in the loopcircuit fails due to the failure of one or two lamps, the switch willnot operate. If the current fails due to a break in the circuit at aplace other than the lamp filaments, the voltage across the cut-out BIwill continue to rise to the film rupturing value of the device BI andwill cause an operation of the switch.

By my invention I provide an improved latching device for the switchmembers I0 and II. When the switches have been opened by reason of thefailure of the film cutout, the switches remain latched in the openposition until the film cutout has been renewed and the holder replacedin the socket. The danger of the re-energization of the broken loopcircuit due to the failure or deenergization of the trip coils is,therefore, eliminated.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. In an automatic switch, the combination of a pair of contacts, anormally-closed switch member for connecting said contacts in apredetermined relation, operating means including a coil for operatingsaid normally-closed switch member to its open position, a film cut-outdevice connected in series with said coil in shunt to said contacts forenergizing said coil when a predetermined potential exists across saidtwo contacts, a latching device'for latching said switch member in theopen position when moved thereto by said operating means, a holder forsupporting said film cut-out device, and means operated by said holderfor unlatching said switch member.

2. In an automatic switch, the combination of a pair of contacts, aswitch member for connecting said contacts in a predetermined relation,means including an operating coil for operating said switch member todisconnect said contacts, a film cut-out device connected in series withsaid operating coil in shunt to said contacts for energizing said coilwhen a predetermined potential exists across said contacts, a latchingmechanism for holding said switch member in the open position, aremovable holder for said film cut-out device, a socket therefor, meansoperable by said holder for shunting said coil and film cut-out devicewhen said holder is removed from said socket, and means for unlatchingsaid switch member operated by said holder when it is inserted into saidsocket.

3. In an automatic switch, the combination of a pair of contacts, anormally-closed switch member for connecting said contacts in apredetermined relation, a normally-open switch member for shunting saidcontacts, operating means including a coil for operating saidnormallyclosed switch member to its open position, a film cut-out deviceconnected in series with said coil across said twocontacts forenergizing said coil when a predetermined potential exists across saidtwo contacts, an operating shaft for said normally-open switch member, alatching device for latching said normally-closed switch member in theopen position, and means operable by said shaft for unlatching saidswitch member.

4. In an automatically-operated switch, the combination of a pair ofmain circuit contacts, a pair of secondary circuit contacts, and a pairof shunting contacts, a. pair of normally-closed switch members forconnecting said main circuit contacts to said secondary circuit contactsrespectively, a normally-open switch member for connecting said maincircuit contacts to each other, means including a pair ofnormally-docuergizedcoils connected in series with an insulating filmfor opening said normally-closed switch members when said insulatingfilm, is broken down, a latching device for maintaining saidnormally-closed switch members in the open position including anoperating shaft for said normally-open switch member, a latching pawlmovable to latching position when said magnet operates to open saidnormally-closed switch members, a releasing pawl, and means includingsaid shaft and releasing pawl for moving said latching pawl to itsrelease position;

5. In an automatic switch, the combination of a film cut-out, aholdertherefor, a switch member, means for moving said switch member toopen position when said film cut-out breaks down, means for latchingsaid member in the open position including a pivotally mountedbell-crank having an arm arranged to engage said switch member and to bemoved therewith by said switch-opening means, a latching pawl arrangedto engage the'other arm of said bell-crank and to move to lockingposition when said bell-crank is moved by said switch-opening means,means for moving said latching pawl to release said bellcrank includinga releasing pawl arranged to engage said latching pawl, and meansincluding said film cut-out holder for operating said releasin Dawl.

6. In a cut-out device, the combination of a pair of main circuitcontacts, a pair of loop circuit contacts, a switch member normallybiased to connect said main circuit contacts to said loop circuitcontacts respectively, a circuit con nected between said main circuitcontacts including a trip coil and a film cut-out device in seriestherewith arranged to break down and pass current when a predeterminedvoltage exists between said contacts, an armature operated by said tripcoil to open said switch member when said trip coil is energized,latching means for said switch member for latching it in open positionincluding a. bell-crank pivoted at its vertex hav'- ing one arm engagingthe switch member, a,v

latching pawl engaging the other arm of said bell crank, means formoving said latching pawl into position to latch said bell-crank in theopen switch position, and means for moving said pawl to release saidbell-crank including a releasing pawl pivotally mounted on a shaft, saidshaft operating a switch member for connecting said main circuitcontacts to each other, a holder for said film cut-out arranged toengage raid shaft and hold it against its bias when the film cutout isconnected in the trip circuit, said shaft being biased to connect saidmain circuit contacts to each other when said holder is withdrawn torenew the film cut-out and to disconnect said contacts when the holderis replaced, said releasing pawl engaging said latching pawl for movingit to the release position when said shaft moves to separate said maincircuit contaets.

7. In a series cut-out switch, the combination of a switch member fornormally connecting a loop circuit to a main circuit, means including anoperating coil ior moving said switch member to open position, a filmcut-out device connected in series with said coil and made to permitcurrent flow through said coil upon application of a predeterminedvoltage across the terminals of said loop circuit, a holder for saiddevice, latching means for holding said switch member in open positionindependently of said coil, and means operable by said holder forunlatching said switch member.

8. In a series cut-out switch, the combination of a switch member fornormally connecting together parts of a series circuit, means includingan operating coil arranged when energized to move said switch member toopen position, a film out-out device connected in series with theoperating coil in shunt to one part of said circuit and made to passcurrent after the application of a predetermined voltage across theterminals of said part, a holder for said cut-out device, a socket forsaid holder, a latching mechanism for latching said switch member intothe open position when moved to that position by said operating coil,and means operated when said holder is placed into said socket forunlatching said switch member.

9. In a series cut-out switch. the combination of a switch member fornormally connecting a loop circuit to a main series circuit, meansincluding an operating coil for moving said switch member to openposition, a second switch member arranged to be normally open and toshunt said loopcircuit when moved to its closed position, a film cut-outdevice connected in series with said operating coil and made to passcurrent upon the application of a predetermined voltage across theterminals of said loop circuit, a latch-v and to shunt said loop circuitin its closed position, a film cut-out device connected in series withsaid operating coil and made to pass current upon the application of apredetermined voltage across the terminals of said loop circuit, alatching mechanism for latching said switch member into the openposition; means for ,unlatching said switch member, and a holder forsaid film cut-out device for operating said unlatching mechanism andsaid second switch member in such manner that said switch member will bemoved to closed position before said second switch member is moved tosaid open position.

11. In an automatic switch, the combination of a pair of contacts, aswitch member for connecting said contacts in a predetermined relation,means including an operating coil for operating said switch member todisconnect said contacts, a film cut-out device connected in series withsaid operating coil across said contacts for energizing said coil when apredetermined potential exists across said contacts, a latchingmechanism for holding said switch member in the open position, aremovable holder for said film cut-out device, a socket therefor, meansoperable by said holder for shunting said coil and film cut-out devicewhen said holder is removed from said socket, and means operable by saidholder for unlatching said switch member and for interrupting said shuntabout said coil and film cut-out device when said holder is insertedinto said socket.

12. In an automatic switch, the combination of a pair of contacts, aswitch member for connect-- device when said holder is removed from saidsocket and r eans operable by said holder when inserted into said socketfor unlatching said switch member and for interrupting said shunt aboutsaid coil and film cut-out device in such manner that the contacts willbe connected by said switch member before said shunt circuit is broken.

13. In an automatic switch, the combination of a pair of contacts, aswitch member for connecting said contacts in a predetermined relation,means including an operating coil for moving said switch member todisconnect said contacts, a film cut-out device connected in series withsaid operating coil across said contacts for energizing said coil when apredetermined potential exists across said contacts, a latchingmechanism for holding said switch member in the open position, means forsupporting said film cut-out device, means operable by said supportingmeans for establishing and for breaking a shunt circuit about said coiland film cut-out device, and means operable by said supporting means forunlatching said switch member before said shunt circuit is broken.

14. In an automatic switch, the combination of a pair of contacts, anormally-closed switch member for connecting said contacts in apredetermined relation, means including an operating coil for operatingsaid normally-closed switch member to its open position, a film cut-outdevice connected in, series with said coil across said contacts forenergizing said coil when a predetermined potential exists across saidcontacts, a latching device for latching said switch member in the openposition when moved thereto in response to the energization of saidcoil, means for supporting said film cut-out device, and means operableby said supporting means for unlatching said switch member.

FREDERICK A. WEIGEL.

